<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    <h2>当前计数: {{counter}}</h2>

    <button v-on:click="add">+</button>
    <button v-on:click="sub">-</button>

    <!-- <button v-on:click="counter++">+</button>
    <button v-on:click="counter--">-</button> -->
  </div>


  <script src="../js/vue.js"></script>
  <script>
    // 语法糖: 简写
    // proxy
    const obj = {
      counter: 0,
      message: 'abc'
    }

    const app = new Vue({
      el: '#app',
      data: obj,
      methods: {
        add: function(){
          console.log("add被执行");
          this.counter++
        },
        sub: function(){
          console.log("sub被执行")
          this.counter--
        }
      },
      beforeCreate: function(){
        console.log('beforeCreate');
      },
      created: function(){
        console.log('created');
      },
      mounted: function() {
        console.log('mounted');
      }
    })

    // 1. button 元素
    // 2. 添加监听事件
  </script>
</body>
</html>
